In order to fill one or more underground storage tanks at a gasoline service station, a cargo tank truck typically pulls into the service station and unloads the fuel from the truck into the underground storage tank or tanks. Such a cargo tank truck commonly has multiple fuel storage compartments, each compartment having a cover and a pipe located below the tank to which is connected a valve assembly. The valve assembly is commonly a poppet valve assembly which is opened and closed by the truck's driver via a handle extending upwardly from the valve assembly. In order to unload fuel from one of the truck's fuel storage compartments into the underground storage tank, the truck driver or operator connects two hoses from the truck to elbows on the underground storage tank. One of the hoses is a vapor recovery hose which returns vapors to the truck from the underground storage tank. The other hose is connected at one end to one of the valve assemblies on the truck via an adaptor and at the other end to the underground storage tank. In order to cause fuel to flow through this hose to the underground storage tank, the truck driver simply opens the valve assembly.
Commonly, each underground storage tank has a valve therein, which closes when the underground storage tank is sufficiently full, thereby stopping the flow of fuel from the truck to the underground storage tank. After this valve in the underground storage tank closes, gasoline or fuel is still present in the line or hose extending between the cargo tank truck compartment and the underground storage tank. In order to prevent gasoline from overflowing onto the pavement of the service station, the operator of the cargo tank truck closes the valve assembly on the cargo truck and opens one of the cam arms on the adaptor, thereby allowing air to enter the hose. The air in the hose forces the fuel in the hose towards the underground storage tank and through a bleeder hole in the valve in the underground storage tank. After a sufficient time period has passed, the operator simply disconnects the adaptor from the valve assembly, removes the hose from the elbow of the underground storage tank and places the hose on the truck. After the vapor recovery hose is disconnected and placed on the truck the driver may move to the next location.
In order to prevent an accidental overflow, it is desirable for the cargo tank truck operator or driver to know if liquid is present in the valve assembly, and if liquid is flowing through the valve assembly. The operator does not want to disconnect the adaptor from the valve assembly of the truck with liquid present in the valve assembly or flowing therethrough. Consequently, it is advantageous for the driver to know whether fluid is present in the valve assembly and whether the flow of fuel through the hose has stopped.
Poppet valve assemblies are known which have a sight glass built therein in which a float is located in order to indicate liquid presence in the valve assembly. The float commonly comprises a hollow ball. When liquid is present in the sight glass, the float raises because its density is less than the density of gasoline. Thus, the operator is able to tell whether fuel is present in the valve assembly. U.S. Pat. No. 6,679,291 discloses such a poppet valve assembly with a sight glass on one side of the valve housing.
When unloading fuel from a tanker truck, it is desirable to know which type of fluid is passing through the valve assembly into the underground storage tank. This is important to ensure that the correct fuel is being placed in the correct underground storage tank. Motor fuels are dyed different colors to aid in their identification. For example, diesel may be colored red while a certain type of unleaded fuel may be colored yellow and another type of unleaded fuel colored blue. Different methods have been used to allow an operator to view the color of the fuel either before the valve assembly is opened to allow fuel to flow through the valve assembly into its desired location or while fluid is flowing through the valve assembly.
One such method, shown in FIGS. 1 and 1A, involves securing a sight glass between the mounting flange of a discharge pipe of the truck and a poppet valve assembly. One disadvantage with using this type of in-line sight glass is that the sight glass is highly stressed by the bolts that attach it to the mounting flange of a discharge pipe of a truck. The result is that the sight glass has a short lifespan and must be replaced often. Due to the large size of such a sight glass, repair is costly and may remove the tanker truck from operation for a lengthy period of time.
Another method, shown in FIGS. 2 and 2A, involves securing a sight glass assembly between the mounting flange of a discharge pipe of the truck and a poppet valve assembly. This sight glass assembly uses a smaller sight glass than the one described in the above paragraph. This sight glass is contained within a metal brace. Therefore, the metal brace, as opposed to the sight glass, bears the stresses imposed by the mounting bolts. One disadvantage with using this type of in-line sight glass is that from a distance it may be difficult to view the color of the fuel, and therefore the type of fuel, passing through the sight glass. Another disadvantage with using this type of in-line sight glass assembly is the high cost of the sight glass assembly due to its multiple components and required assembly.
Each of these methods requires securing an element or elements between the mounting flange of the discharge pipe on the truck and the mounting flange of a poppet valve assembly, thereby increasing the chance of leaks or spills while increasing the cost of assembly, i.e. more labor. Therefore, it has been one objective of the present invention to provide a poppet valve assembly having an in-line sight glass incorporated into the poppet valve assembly which enables one to determine whether fuel is present in the poppet valve assembly from a distance and if so, which color fuel or fuel type.